Add Documentation for Federated operations

[d47853]

Add a section for FederatedStore operations such as:

• AddGraph
• AddGraphWithHooks
• RemoveGraph
• GetAllGraphIds
• ChangeGraphAccess
• GetAllGraphInfo

[GCHQDeveloper314]

Now consists of these operations to be added to the reference section:

• federatedstore.operation.AddGraph
• federatedstore.operation.AddGraphWithHooks
• federatedstore.operation.ChangeGraphAccess
• federatedstore.operation.ChangeGraphId
• federatedstore.operation.FederatedOperation
• federatedstore.operation.GetAllGraphIds
• federatedstore.operation.GetAllGraphInfo
• federatedstore.operation.RemoveGraph
• federatedstore.operation.RemoveGraphAndDeleteAllData

[GCHQDeveloper314]

Most of these operations are covered by the Federated Store guide. In #416 it's been mentioned that a guide is not the best place for them. As part of this issue, operation specific documentation from that guide can be moved to the reference section.

[GCHQDeveloper314]

Also ensure that the operation examples use the same format (examples in JSON, Java, Python) as found elsewhere in the reference guides. The examples currently in the Federated Store guide don't include Python or use the compact code tabs formatting.